The exploration of adaptation has been a keystone of evolutionary biology research since Darwin published Origin of Species. Despite this long history of investigation, the genetic basis of adaptation has only recently been studied in a comprehensive manner, primarily because until recently, the necessary genetic and genomic technologies were unavailable. One signature of adaptation in species with high migration rates is genetic differentiation between populations of the same species. In such cases, local selection in different environments is strong enough to overcome the homogenizing force of gene flow. The proposed work seeks to explore the genomics of adaptation along latitudinal clines in the genetic model system, Drosophila melanogaster. The work will use microarray analysis, DNA sequencing, and genetics, to describe variation in genes (and the associated phenotypes) influenced by spatially varying selection in D. melanogaster.